Refrigerating machine



Oct. 23, 1828. 1,688,589

l. LUNDGAARD y REFRIGERATING MACHINE Filed Feb. '7, 1924 INVENTOR MM' www Patented Oct. 23, 1928.

IVAR LUNDGAARD, 0F HARTFORD, CONNECTICUT, ASSTGNOR, BY MESNE ASSIGN- MENTS, TO DEVON MANUFACTURING COMPANY,

CORPORATON 0F MASSACHUSETTS.

OF BOSTON, MASSACHUSETTS, A

BEFRIGERATING MACHINE.

Application filed February 7, 1924. Serial No. 691,165,

This invention relates to automatic refrigerating machines involving the use of air as a medium, such as is shown in my prior Patent No. 1,240,862.

My present invention relates more particularly to a means of increasing the average pressure ot the mediating air and to this end, it comprises an auxiliary air pump, mounted in the crank case and articulated with the moving members of the air Compressing mechanism, which pump operates to draw air from the atmosphere and torce the same into the crank case, thereby keeping the pressure in the crank case al deiinite amount above atmospheric pressure. As the pressure in the crank case is the minimum pressure of the air compressing cycle, the average pressure of the cycle is, therefore, raised, by means of the auxiliary pump, any desired amount.

In the drawings:

Figure 1 represents a section through the portion of the crank case, upon which the pump is mounted at right angles to the driving shaft.

Figure 2 is a. section through the pump parallel with the driving shaft.

Figure 3 shows a modification.

ln the embodiment shown in the drawings, 1 represents the driving shaft of the refrigerating machine and 2 the ends of Connecting rods articulated therewith and being driven thereby. 3 represents a crank case of the retrigerating machine and in a depressed portion ot the bottom ot the same is attached. the cylinder 4L ot the auxiliary pump. A piston plunger 5 is adapted to be reciprocated in the cylinder by means ot the cross head 6 and connecting link 7, which unite the same to the corner ot the aforesaid connecting rod 2. From this itA will be seen that the rocking motion of the connecting rod will impart a reciprocating motion to the plunger 5. Air is admitted to the pump from the atmosphere through a calcium chloride box 8, wherein the air is freed of its moisture before entering-pupo 9, which leads to a vertical duct 10, the lower end ot' which dips into a mercury seal 11. At the lower end ot the duct, a ball 12 may be used to check the outflow of air from the pump. The height of the mercury column in the duct 10 will also Yact as acheck. The casing 13, surrounding the duct 10 and holdmg the mercury trap, opens yinto a duct 14 that leads to the pump cylinder,Vv A dis; charge duct 15 leads from the pump cylinder into the crank case and has a check valve 1G for preventing the air returning from the crank -case to thecylinder. This duct 15 eX"- tends into the cylinder chamber to a point near the bottom. This is in order toinsure that any oil in the cylinder will be driven out in advance ot' the air. The volume ot the clearance in the cylinder, in the duct 111 and in the chamber 13, should be made such that the pressurer established in the crank case by the pump will not be too great and itwill be Seen that the .fixing of this volume establishes definitely the maximum pressure to be attained in the crank case. yIt becomes important, therefore, to prevent any accumulation or' oil in the clearance space as such accumulation would, of course, bring about a decrease inthe clearance and an increase in the delivery pressure. It will be apparent also that any surplus oil running into the suction chamber 13 will be immediately pumped out and into the crank case.A The bottom ot the crank case will always con,- tain considerable oil, which serves to lubricate the moving parts ot the machine. From the crank case, the air passes to the cylinder by duct 16 in the sidev otl trie cylinder wall 17, when the piston 18. is at its lowermost position. It' desired, the ball check, shown at 12, may be'omitter in which case the mercury column 11 will act to prevent any escape of air during the .pressure stroke` of the pump. On the suction stroke, the mercury will all run out of the duct 10 and 'will allow the admission of the air. Owing to the relative sizes .of the chamber 13 and the column 10, very little change in level ot the mercury inthe chamber will correspond with a considerable,change in the `height ot vthe mercury columnlO. The height ot this column et mercury may also be used as a means of regulating and limiting the maximum pressure. To make this more definite, means should be provided for limiting the heiglii of the mercury column and to this end there is provided an enlargement of the suctionV conduit at 19 so that when the mercury pas reaches that point, it will spread out hori- Zontally and prevent a 'further increase in head.

In Figure 3 is shown a modified form in which the pump plunger 5 is made hollow so as to forni the delivery outlet iior the pump. The check valve 16 is in this case located in the plunger. To guard against possible leakage of air or oil past the plunger, ai'liecting the clearance, the base oit the pump may be formed with a trapped recess 20 formed, for example, by a depending` flange 21. With such a construction, the clearance and, consequently, the maximum pressure of air delivered by the pump into the crank case will remain iixed and will not be affected by leakage past the plunger or valves.

I claim l. In a machine of the class described comprising a crank, a crank-case and a connecting rod-connected to said crank, the combination with the crank-case oi' an auxiliary air pump adapted to receive atmospheric air and having an outlet port leading into the crankcase.

2. In a machine of the class described comprising a crank, a crank-case and a connecting rod connected to said crank, the combination with the crank-case of an auxiliary air pump adapted to receive atmospheric air and having an outlet passage into the crank-case, said passage connecting with the clearance chamber of the pump near the lowest part thereof, whereby surplus oil in said chamber will be expelled into the crank-case.

3. In a machine of the class described comprising a crank, a crank-case and a connecting rod connected to said crank, the combination with the crank-case of an auxiliary air pump adapted to receive atmospheric air and havin g an outlet port leading into the crank-case, said pump being located substantially below the normal oil level of the crank-case.

4. In a machine of the class described comprising a crank. a crank-case and a connecting rod connected to said crank, the combination with the crank-case ot an auxiliary air pump adapted to receive atmospheric air and having an outlet port leading into the crank-case,

and a check valve in the outlet port adapted to permit flow of air into the crank-case at a determined differential in pressure between the chamber of the pump and the crank-case.

5. In a machine of the class described comprising a crank, a crank-case and a connecting rod connected to said crank, the combination with the crank-case oi an auxiliary air pump adapted to receive atmospheric air and having an outlet passage into the crank-case. said pump'being provided with a clearance chamber and a plunger reciprocable therein. said passage connecting with the clearance chamber of the pump near the lowest part thereof,

whereby surplus oil in said chamber will be expelled into the crank-case, so as to maintain a constant clearance volume.

6. In a machine of the class described comprising a crank, a crank-case and a connecting rod connected to said crank, the combination with the crank-shaft, of a connecting rod and a link both operatively connected to said shaft, an auxiliary air pump, a. plunger in said pump connected to the link, said pump having a port connected to the outer air and a second valve-controlled opening leading intothe interior of the crank-case.

7. In a machine of the class described comprising` a crank, a crank-case and a connecting rod mounted thereon, the combination of an auxiliary air pump, a plunger in said pump, a link operatively connected to said ilunver and articulated to said connectinor t3 D rod, a dryer, said plunger having a port connected to the dryer and adapted to receive dried outer air therefrom and having a weighted check valve to permit air outlet into the machine.

8'. In a machine ot the class described com- 9. In a machine of the class described comprising a crank, a crank-case and a connecting rod mounted upon the crank, the combination oi the crank-shaft, a link operatively connected to said shaft, an auxiliary air pump, a Y

plunger in said pump connected vtothe link, said pump having a port connected to the outer air and a valve-controlled opening leading into the interior oi the crank-case, said valve being' adapted to open when the pressure in the pump exceeds the pressure in the crank-case by a predetermined amount.

10. In a machine of the class described comprising a crank, a crank-case and a connecting rod connected to the crank, an auxiliary air pump, a clearance chamber in said pump, a plunger. reciprocable therein, a valve controlled outlet connecting the clearance chamber with the interior of the crank case, means for actuating the plunger connected to the crank, said outlet being located in the crank case below the lowest position of the connecting rod, whereby oil having a level sufficiently high to be thrown by the connecting rod dip will cover the outlet of the pump and act as an oil seal for the same.

IVAR LUND GAARD. 

